261821145012 has 192 divisors, whose sum is σ = 743863357440. Its totient is φ = 70054972416.

The previous prime is 261821144993. The next prime is 261821145017. The reversal of 261821145012 is 210541128162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261821145017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 53550664 + ... + 53555552.

It is an arithmetic number, because the mean of its divisors is an integer number (3874288320).

Almost surely, 2^261821145012 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261821145012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (371931678720).

261821145012 is an abundant number, since it is smaller than the sum of its proper divisors (482042212428).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261821145012 is a wasteful number, since it uses less digits than its factorization.

261821145012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5502 (or 5500 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 33.

The spelling of 261821145012 in words is "two hundred sixty-one billion, eight hundred twenty-one million, one hundred forty-five thousand, twelve".